Hi Rahul,

thanks for the feedback, I will add it to the driver.

My personal recommendation is to just have a single DMA buffer allocated
for the mcp2200 instance rather than having to call the allocator and
release the memory per command.

I added an 16-byte Array hid_report to the mcp2000 struct. When I need the
report, I do the following:

struct mcp_set_clear_outputs *cmd;

mutex_lock(&mcp->lock);
cmd = (struct mcp_set_clear_outputs *) mcp->hid_report

Do you think this is a valid implementation or do I really have to add a
pointer to the mcp2200 struct instead of the 16 byte array and allocate 
another 16 byte for it in the probe function?

The reason you run into this is likely because of the action added to
devm conflicting with hid_device_remove....

I recommend not depending on devm for teardown rather than making a stub
remove function to work around the issue.

I am not sure, if I have understand this correctly, but basically I already
have a stub remove function (which is empty). First the remove function gets
called, then the unregister function and everything is cleaned up correctly.
Did I get this right or do you have any other recommendation for me?

So, do I need any adaptions, or can we go with the empty remove function?

Best regards,
Johannes